ALFAGTV6.COM

[MR2 Zig]

IF....IF what I said/ found about the torsional (twisting) load is right then the best way to go is going to be heavy front flywheel and lighten everything behind the front coupling (including the clutch) for longer life of the coupling. This may not be a good/ useable combo for racing.

Kevin,

Do you get any noise out of your coupling cage at idle or at constant speed going down the road? Or does your exhaust drown out the other noises?

Scott

[kevin]

Scott, I believe the 75 3.0l had a heavier flywheel and lighter clutch over the GTV6. Is that not a progression or just refinement. I saw and drove for the first time a 75 Milano that was brought over from USA today. The car is still new. Sorry deviation.
I have coupling cages on all three cars and you cannot hear them. There is a 4mm gap between them so they do not touch. This also alows for the offset angle of the engine.

[MR2 Zig]

I think that would be a progression on Alfa's part.

With the amount of movement you were talking about I thought maybe the bolts were hitting the ends of the slots on opposite (front/rear) sides of the coupling and maybe making some noise....but I guess that's not happening.

Scott

[mjr]

Take the dulux racing gtv6's as an example. They run on UJ's to eliminate the problem. That surely has to be the answer. What about the group A and B cars from the 80's, they surely did not run donuts.?

[MR2 Zig]

mjr,

you are right in that they probably did something different than donuts. we just need to find out what....or get some really deep pockets and try a bunch of different things.


zig

[MR2 Zig]

I have a question, maybe Mats knows, why is it that industrial couplings are so much bigger than automotive ones for what appears to be the same horsepower? Granted what I see in industrial stuff is for electric motor application.

Reason I ask is that I'm going to start looking at industrial couplers for a solution to our problems.

zig

[mjr]

Zig, Im fairly sure the group C Gtv6's had 2piece shaft with UJ's. but could be wrong? I think the guy that owned the last one used to post on here? (Scott Farquharson)


he posts here these days. maybe worth asking him for some specs and photos

http://www.alfaclubvic.org.au/component ... pic,311.0/

[Greg Gordon]

Zig, I don't know for sure, but I think there are a couple reason industrial couplers are bigger. First of all they have to take a large amount of nearly instantaneous torque. Electric motors can put out a lot of torque very suddenly. The other issue may have something to do with rpm. As you go to larger and larger couplers the forces from the centrifugal effect increase. Don't underestimate these, it works out to thousands of Gs. On an industrial machine this may not be a big factor as they usually turn fairly low rpm. On our cars a coupler with a larger diameter will be more likely to blow with all other things equal.

Greg Gordon,
www.hiperformancestore.com

P.S. I am amazed how much interest there is in improving the Guibos. It's the transmission that's the weak link.

[ar4me]

I think the driver is often the "weak" link abuse will cause failures even on a stock car, while smoth operation will make modified cars last.

On a serious note:

My personal objective is to eliminate the driveshaft as _a_ weak link and a safety risk in a high power car where I have seen evidence of failure (before any transmission issues, excluding clutch).

Greg, when you say that the transmission is the weak link, I wonder if you are basing that on experience where you carefully align driveshaft and cross-bolt transaxle side mounts. Those are non-stock items addressing driveshaft wear, and hence, in stock application the driveshaft could indeed be a weak link.

Then there is also the safety aspect. Many have probably seen the thread on the AlfaBB about the 105 racer who got seriously injured from a failing front coupling causing the driveshaft to whip around. I'm not saying this will happen on the 116 cars, but can we rule it out? I don't want to be the one to find out - better safe than sorry. The front coupling I will be using prevents everything from coming apart up front. Perhaps the cage offers similar protection, though I have never looked at one.

Jes

[MD]

by mjr on Wed Dec 31, 2008 8:50 pm
Take the dulux racing gtv6's as an example. They run on UJ's to eliminate the problem. That surely has to be the answer. What about the group A and B cars from the 80's, they surely did not run donuts.?

by MR2 Zig on Thu Jan 01, 2009 12:03 am
mjr,

you are right in that they probably did something different than donuts. we just need to find out what....or get some really deep pockets and try a bunch of different things.

If you go back over this topic you will see that this stuff has already been covered.

To recap for you..

1 It all depends on what you want to do. Street or race. Do not overlook this.
2 Three uniniversal joints or C.V. joints work but they are very noisey up to around 1800-2000 rpm because during the firing stroke of the engine, there is a loud "hammering" that "rings" up and down the propshaft which sounds like your transmission is about to give up the ghost.
3 One rubber donut at the front fixes the noise problem. In this situation you could use a standard Alfa unit with a can or do a donut PCD conversion and use a BMW one. Both of these applications have been illustrated before by Kevin and me respectively.

Here's some photos of cans available commercially I believe but dont' ask me where. I don't use them.

[kevin]

Perfect summary and the one doughnut also absorbs that shock wave which is the noise you talk about.
Going further down the line i got hold of an autodelta clutch housing. Wow what an improvement in strenght. The webbing is twice as thick and its lighter.

[MD]

Hi Kevin,

I had a change of mind about the reinforcement of the clutch housing "snout". We have fabricated one and will be installing it for the new season. Will let you all know if it works..

The heavy duty Auto Delta unit has to be an admission that the road versions are borderline. If it breaks again with the brace in place, I am making a clutch housing out of steel...

[Jim K]

This is for the insatiable high power group (not really my bag) but its a rece-proven and reliable item (I'm talking about the special donut). In the left column of the initial screen, scroll down and select 'produits', then go to the second page and click 'page suivante'at the bottom:
http://www.scuderiadelbiscione.com/
Jim K.

[ar4me]

This is for the insatiable high power group (not really my bag) but its a rece-proven and reliable item (I'm talking about the special donut). In the left column of the initial screen, scroll down and select 'produits', then go to the second page and click 'page suivante'at the bottom:
http://www.scuderiadelbiscione.com/
Jim K.

That is the coupling I purchased and posted pictures of on page 2. It is the one I will be using up front on the 3.7 24v Milano race car.
Jes

[MD]

JK,

I think (I know that's unusual) that one these guys in the front followed by two CV's is just about the complete answer for these driveshafts other than carbon fibre and/or torque tubes.

When I have some spare time, I just might look into doing this conversion to my road car. Watch this space...